Cross flow metalizing of compact disc

ABSTRACT

A cross flow system for metalizing compact discs, capable of being interposed in-line in the production of the compact discs after premastering, mastering, electro-forming, and molding includes a vacuum chamber having diametrically opposed vacuum locks and multiple metalization sources in the form of magnetrons, with a preferred cross flow including the introduction of a disc to be metalized through one lock and the exit of the metalized disc through the diametrically opposite lock. The double vacuum lock diametrically opposed cross flow system eliminates the problems of throughput limitations, high rate deposition, substrate pitting, and software complexity due to indexing which makes prior systems both costly and inefficient. The system also permits processing of more than one substrate or compact disc title such that multiple titled compact discs can be processed simultaneously.

[0001] This is a continuation-in-part of U.S. patent application Ser.No. 08/355,664, filed Dec. 14, 1994.

FIELD OF THE INVENTION

[0002] This invention relates generally to the fabrication of compactdiscs and more particularly to a cross flow metalization system forincreasing yield and decreasing complexity while permitting in-linemetalization in the compact disc fabrication process.

BACKGROUND OF THE INVENTION

[0003] Compact discs or CDs are currently manufactured in a relativelycomplex process in which the information on the CD is first obtained forinstance from a digital source. A premastering disc is created in aphoto lithographic process which lays down the information in a spiralpattern. From the premastering disc, a master stamping disc is formed inan electroplating process. The master stamping disc is then used to hotstamp thermoplastic discs with the grooves or interstices which carrythe information from the premastering disc.

[0004] Following the molding of the discs, the discs are “metalized” byplacing them, via a vacuum lock, into a vacuum chamber where a thin coatof aluminum is deposited over the physical patterning on the surface ofthe disc (“substrate”) using a sputtering device comprising a magnetron.After metalization, the discs are spin coated to cover the metal with aprotective coating such as lacquer. This is usually followed by aninspection step.

[0005] Compact discs were originally fabricated in a batch process inwhich individual discs were taken from station-to-station. Presentprocessing requires continuous processing along an efficient flow pathto take the discs from start to finish, so that more than 1,000 discsper hour can be manufactured.

[0006] The metalization step has caused significant throughput andquality problems in the past. Initially, the metalizer was locatedoff-line (i.e., out of the main, direct line process flow) due to itssize and complexity. These units simply could not conveniently belocated in the flow path, but rather had to be located off to one sidewith resultant materials handling problems and complexity.

[0007] Metalizers can now be made part of the flow path and arecurrently available from Leybold in Germany and Balzers inLiechtenstein. The standard metalizers from these companies are similarin design and throughput performance. Both have rotational transportmechanisms which use a dial inside of a vacuum chamber for thetransportation of a plurality of substrates (e.g., thermoplastic discs)under a single deposition source which includes a magnetron. Adjoiningthe vacuum chambers are external rotational transport mechanisms forbringing the substrates (discs) in and out of the vacuum chamber througha single vacuum lock. Internal and external transport mechanismssequentially carry out the loading and unloading of the substrates.

[0008] These metalizers have permitted increased throughput by providingcontinuous processing. However, the continuous process permits only onetitle to be run at one time through the molding, metalizing, spincoating, and inspection process. This makes the overall investment forCD manufacturing very high because one metalizing machine must beassigned to each molding system.

[0009] It will be appreciated that for compact disc production, ordersfor compact discs are frequently in the hundreds as opposed to thousandsor tens of thousands. Thus, it is very important to be able to eitherprocess different titles simultaneously or increase throughput speed tomaintain the efficiency of the entire line.

[0010] Throughout speed is frequently increased by decreasing the dwelltime under the sputtering device. This is accomplished by moving themagnetron closer to the substrate. However, this approach decreasesoverall quality of the disc and can render high density informationdiscs unusable.

[0011] A different approach to increasing throughput speed and alsopermitting the simultaneous processing of multiple titles, has beendeveloped by Leybold—a double magnetron, double vacuum lock system.Theoretically, this approach should increase disc throughput twofold.However, these machines require the disc to exit to the same vacuum lockit entered resulting in an inordinate amount of indexing complexitywhich significantly diminishes the theoretical increase.

[0012] Leybold's double lock machines have exceedingly large diameterdials, often greater than five feet. The sheer size of the vacuumdeposition chamber to accommodate such large dials inhibits theinsertion of this machine into the production line, to say nothing ofthe cost of the relatively large unit. With the use of this device acomplicated process flow path is thus, inevitable.

[0013] The double magnetron machines also require a double index step inwhich “odd numbered” discs are processed by one magnetron and “evennumbered” discs are processed by the second magnetron. However, withthese machines, the both discs must pass under both magnetrons. It willbe appreciated that with this approach, indexing errors rapidly becomesignificant. When such errors occur during the processing of multiple CDtitles, the titles become mixed up such that all of the mixed up discsmust be discarded, as there is no way of identifying which disc wasassociated with which title.

[0014] More particularly, when multiple titles are to be processed, thediscs of a single title are loaded onto discrete spindles, with anaverage of six spindles being utilized during a run. These spindles eachtypically hold as many as 200 CDs. If during the process indexingproblems occur, then the entire lot may have to be discarded because themanufacturer must guarantee the discs loaded on a given spindle come outwith the same titles.

[0015] Thus while the double magnetron, double vacuum lock systempermits processing of multiple titles simultaneously, the potentialindexing problems are so severe that such processing is generally notpractical.

[0016] There is therefore a necessity for providing an in-line systemwith efficient metalizing in which indexing problems are reduced to aminimum while at the same time being able to process multiple titles, toaccommodate short production runs.

SUMMARY OF THE INVENTION

[0017] The present invention is an improved metalizer which, rather thanemploying a single vacuum lock, single magnetron system or a multiplemagnetron system with each vacuum lock handling the same disc on entryand exit, is directed to a system in which the vacuum locks throughwhich discs are introduced into the vacuum chamber are different fromthe vacuum locks through which the discs exit the vacuum chamber. Thisapproach permits not only the creation of a smaller metalizer which iscapable of being interposed in a linear process flow path, but alsoeliminates the interleaving of discs during the metalization process andthe associated, inevitable indexing problems. In one embodiment thepresent invention permits the use of a dial having as few as four disccarriers within the vacuum chamber, versus utilization of a more thantwelve disc carrier dial within a vacuum chamber for a Leybold doublemagnetron metalizer.

[0018] In a preferred embodiment of the present invention the vacuumlocks are diametrically opposed to each other on either side of thedial. Moreover, the magnetrons utilized to metalize the discs are alsodiametrically opposed to each other on opposite sides of the dial suchthat the flow of a disc from input lock to exit lock requires that thedisc travel under only one magnetron. For purposes of carrying out theinvention, the magnetrons need not be diametrically opposed but ratherneed only be on different sides of the dial. While it is preferable tohave the input and exit locks diametrically opposed to be able to mostefficiently operate with a linear flow of product, the vacuum locks maybe offset one from the other as required. It should be noted, however,that a non-diametric arrangement of the input and exit locks expands theoverall size of the equipment.

[0019] In operation, a disc having a first title enters the vacuumchamber from a first lock, is moved around the dial, is metalized, andexits at a second lock preferably located opposite the first lock. Asecond title enters the vacuum chamber via the second lock and is movedaround with the dial in the opposite direction, horizontally speaking,from the direction of movement of the first-title, to produce a “crossflow”. After metalizing, the second title exits the vacuum chamber viathe first lock. Thus, the flow of product in one direction is for onetitle, while the flow of product in the other direction is for thesecond title. This flow pattern guarantees title integrity as allproduct emerging from a given lock must be associated with one title.Thus, the present invention provides title integrity while alsoproviding a substantially higher throughput with a better economy ofmachinery.

[0020] With the improved throughput, standard deposition rate sourcesmay be employed at either increased spacing between the magnetron andthe disc or at lower electric consumption rates to prevent pitting.Thus, one and a half times the production rate achievable with priormachines can be achieved without comprising product quality.

[0021] Additionally, if a single magnetron metalizer is made inaccordance with the present invention it can be instantly ungraded inthe field simply by adding a second magnetron at a second position. Thisis not possible with the majority of present metalizers since they haveonly a single vacuum lock, and would thus, have to be remanufactured toprovide a second vacuum lock.

[0022] In summary, a cross flow system for metalizing compact discs,capable of being interposed in-line in the production of the CDs afterpremastering, mastering, electro-forming, and molding preferablyincludes diametrically opposed vacuum locks for a vacuum chamber andmultiple metalization sources in the form of magnetrons, with a crossflow including, the introduction of a disc to be metalized through onelock and the exit of the metalized disc preferably through adiametrically opposite lock. The double vacuum lock, diametricallyopposed cross flow system eliminates the problems of throughputlimitations, high rate deposition, substrate pitting, and indexingsoftware complexity which makes prior systems both costly andinefficient. The system also permits processing of more than onesubstrate or CD title such that multiple CD titles can be processedsimultaneously.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] These and other features of the subject invention will be betterunderstood in conjunction with the Detailed Description taken inconjunction with the Drawings of which:

[0024]FIG. 1A is a schematic and block diagram of a prior art line forthe production of compact discs;

[0025]FIG. 1B is a schematic and diagrammatic illustration of a processfor the fabrication of compact discs having an inline flow pathincluding an in-line metalizer;

[0026]FIG. 2A is a diagrammatic illustration of a prior art metalizationchamber utilizing a single magnetron and a single vacuum lock;

[0027]FIG. 2B is a diagrammatic illustration of the prior art singlechamber, single vacuum lock metalization unit described in connectionwith FIG. 2A;

[0028]FIG. 3 is a diagrammatic top view of the prior art single port,single magnetron metalization unit;

[0029]FIG. 4 is a diagrammatic and top view of a prior art multi-port,multi-magnetron system in which compact discs enter and exit the samevacuum lock.

[0030]FIG. 5 is a diagrammatic representation of the Subject metalizingsystem utilizing diametrically opposed vacuum locks used for loading andunloading discs and double magnetron metalization stations within avacuum chamber to implement cross flow processing;

[0031]FIG. 6 is a cross sectional view of a portion of a compact discwhich has been metalized in accordance with the Subject Invention;

[0032]FIG. 7 is a top schematic view of the Subject metalization unitillustration diametrically opposed input and exit vacuum locks andmultiple magnetrons, also illustrating a cross flow system for productflow through the vacuum chamber; and

[0033]FIG. 8 is a perspective view of the substrate lock of the presentinvention.

DETAILED DESCRIPTION

[0034] Referring now to FIG. 1A, after a premastering step produces amaster of the particular program material or content of the disc andafter electroplating, the master provides a hot stamping, embossing, orstamping plate, used in the molding of an individual disc as illustratedat 10. This step is followed in the prior art with off-line metalizationaccomplished through a metalizer 12. After metalization of the disc, thedisc is spin coated at 14 and inspected at 16 which returns thecompleted disc to a spindle module 18 where it is available for printingand packaging.

[0035] It will be appreciated that in the flow process illustrated inFIG. 1A, the metalizer is located off-line due to its single portconfiguration. By off-line it is meant that the metalizer is notserviced by the main conveyor used to transport the molded disc throughthe system.

[0036] In contradistinction as shown in FIG. 1B, a metalizer 12′islocated in-line with the flow of product from the molding stationthrough the metalization station to the spin coating station. Withcurrent technology, the inspection station can also be brought in-linewith the spin coating station and the spindle module.

[0037] Referring to FIG. 2A, a prior art metalizer 12 as shownschematically in FIG. 1A, includes a chamber 20, located above a pumpand drive housing 22 directed by a microprocessor housed in ControlsCabinet 40. A vacuum lock manipulator 24, picks up discs 26, after theyhave exited the molding apparatus 10. The manipulator rotates and movesup and down in a vertical plane to bring the unmetalized discs to theentrance to the single vacuum lock of the chamber. The discs are broughtinto the chamber and placed in a substrate holder 30 within a dial 32which rotates the discs under a metalizing unit in the form of amagnetron 34. The features of this prior art metalizer are shown in moredetail in FIG. 2B. in which disc 26 is located within substrate holder30 located within dial 32, with like reference characters referring tolike elements between these two figures.

[0038] Referring to FIG. 3, such single magnetron, single vacuum lockmachines are connected to an external transport 42 from which themanipulator 24 obtains a disc 44. The manipulator 24 places the disc 44through vacuum lock 46 into the substrate holder 30 positioned at thevacuum lock. Disc 44 is revolved around in the direction of arrow 45 viamovement of rotary dial 30 until it is positioned underneath magnetron34. At this point the metalization of the surface of the disc isaccomplished. The disc is then moved back towards vacuum lock 46.

[0039] A two magnetron, two vacuum lock metalizer is shown in FIG. 4.These metalizers also include a rotary dial 58 which, is upwards of 5feet in diameter with 24 substrate holders 60 which are divided for easeof reference into odd and even numbered substrate holders.

[0040] In operation, discs of the first title, here labeled “1” areloaded into the vacuum chamber (not shown) at vacuum lock 54, where theyare placed in the substrate holder currently at that position. Thesecond title, here labeled title “2”, is loaded through vacuum lock 56into a substrate holder designated with an even number. By use of anindexing system (not shown), the discs are positioned under one or theother magnetron, so that magnetron 52 metalizes only the second titleand magnetron 50 metalizes only the first title. This indexing patternalso causes the first and second titles to exit through the same vacuumlock each respectively entered. As noted above, when indexing problemsoccur with this system, all of the discs in the run have to bediscarded.

[0041] Referring now to FIGS. 5 and 7, unlike the prior art systems, themetalization unit 70 of the present invention is interposed in the linein which load lock manipulators 72 and 76 can each receive incomingdiscs 74 from a molding apparatus.

[0042] The load lock manipulators 72 and 76 each bring their respectivenewly molded disks to an aperture above a vacuum lock—aperture 96 andvacuum lock 98 for manipulator 72 and aperture 104 and vacuum lock 106for manipulator 76—for entry into the vacuum chamber 78. Discs enteringthrough vacuum lock 106 (“A” discs), move around the “top” of the arcdefined by the dial 100 (as shown in FIG. 7), passing under magnetron82. After being metalized via magnetron 83 (the end result of which isshown in FIG. 6 where the metal coating is designated 89 and thesubstrate is 88) these discs are passed out of the vacuum chamber 78through vacuum lock 98 where they are picked up by manipulator 72.Conversely, discs which enter vacuum chamber 78 via vacuum lock 98 (“B”discs), pass along the “bottom” of the arc under magnetron 80 and exitvia vacuum lock 106. This procedure and configuration thus,substantially reduce indexing complexity and the likelihood of indexingerrors.

[0043] In one preferred embodiment of the present invention Disc “A” andDisc “B” are the same title being metalized via a cross flow pattern. Inanother embodiment, Disc “A” and Disc “B” represent different titlesbeing simultaneously metalized and flowing in and out of the metalizerin different directions (i.e., in the cross flow pattern).

[0044] In yet another preferred embodiment of the present invention, thesecond magnetron 80 is eliminated and the disc flow is only along the“top” of the arc of dial 100. Obviously, such a configuration lendsitself to the simple addition of second magnetron 80 at a later time.

[0045] In still further embodiments of the present invention, the sizeof the dial 100 can be expanded to include more substrate holders toprovide space for additional vacuum locks, manipulators and magnetrons.In other words, but for space considerations and manipulatorinterference, an unlimited number of vacuum locks and magnetrons, inpairs, can be employed to increase processing throughput and titlehandling. For example, adding one more magnetron and one more vacuumlock could allow the present invention to simultaneously process threetitles. It will be appreciated by one of skill in the art however, thatthese additions can significantly complicate flow paths and materialshandling to the point where no useful gain is realized.

[0046] A further feature of the present invention is shown in FIG. 8.That is, the presence of a substrate lock 120 associated with acentering pin 122 used in conjunction with the substrate holder. Thecentering pin 122 is used with prior art devices to precisely locate thesubstrate in the substrate holder. However, because of the rotationalspeeds of the dial 100 possible with the present invention, thesubstrates could become disengaged from the substrate holder. As such,the provision of substrate lock 120, preferably in the form of springbiased steel balls, provides the ability to maintain the precisionplacement of the substrate in the substrate holder, throughout thesubstrate's travel through the vacuum chamber.

[0047] What has been achieved is a materials handling system whichsignificantly improves the quality and speed with which compact discs orother articles can be manipulated through a vacuum chamber in a crossflow process in which, in a preferred embodiment, entrance and exitlocks are diametrically opposed. The system is not only capable ofhandling compact discs which must be metalized but is also useful insemi-conductor processing in which various other substrates such assemiconductor wafers, ceramics, plastics and metals can be metalized viavacuum deposition or otherwise processed via the cross flow.

[0048] While reference has been made to certain preferred embodiments ofthe present invention, these are meant as illustrative only and it willoccur to those skilled in the art that modifications can be made withoutdeparting from the spirit or intent of the invention.

1. An apparatus for the metalizing of substrates comprising: a vacuumchamber having a plurality of vacuum locks communicating therewith forfacilitating the ingress and egress of substrates from and to theambient atmosphere; means for evacuating air from said chamber; asubstrate carrier located in said chamber; means for providing a supplyof substrates for introduction to said chamber through at least one ofsaid vacuum locks; means for introducing substrates to said chamberthrough said vacuum locks; means for positioning said substratesintroduced via said vacuum locks in said substrate carrier; at least onesputtering means located within said chamber; means for moving saidsubstrate carrier to position substrates under said sputtering means fora predetermined period of time; means for activating said sputteringmeans in timed relationship to the passage of substrates therebeneath;and means for removing substrates from said chamber via a differentvacuum lock than the vacuum lock through which the substrates enteredsaid chamber.
 2. The apparatus of claim 1, wherein each of saidsputtering means includes a magnetron.
 3. The apparatus of claim 1,wherein each of said vacuum locks includes an aperture communicatingwith said means for introducing substrates to said chamber for theintroduction of discs therethrough.
 4. An apparatus according to claim1, wherein said chamber is circular and said substrate carrier is in theform of a dial rotationally movable in said chamber.
 5. An apparatusaccording to claim 4, wherein said apparatus comprises first and secondvacuum chambers and first and second sputtering means.
 6. An apparatusaccording to claim 5 wherein said first and second vacuum chambers arepositioned opposite each other along said substrate carrier.
 7. Anapparatus according to claim 6, wherein said first and second sputteringmeans are positioned opposite each other in said chamber along saidsubstrate carrier.
 8. An apparatus according to claim 7, wherein saidsputtering means and said vacuum locks are arrayed alternately aroundsaid chamber.
 9. An apparatus according to claim 8, wherein saidsubstrates entering said chamber via said first vacuum lock travel in alinear direction opposite the linear direction of travel of substratesentering said chamber via said second vacuum lock.
 10. An apparatusaccording to claim 4, wherein said substrates are compact discs.
 11. Anapparatus according to claim 4, wherein said substrates aresemiconductor wafers.
 12. An apparatus according to claim 4, whereinsaid substrates comprise plastic.
 13. An apparatus according to claim 4,wherein said substrates comprise ceramic.
 14. An apparatus according toclaim 4, wherein said substrates comprise metal.
 15. A method ofmetalizing substrates comprising: providing a supply of substrates;introducing substrates to a vacuum chamber through a first vacuum lock;passing said substrates under sputtering means for a predeterminedamount time to metalize said substrate; and removing said metalizedsubstrates from said vacuum chamber via a second vacuum lock.
 16. Amethod according to claim 15, further comprising the step of adding asecond sputtering means such that: substrates are also introduced tosaid vacuum chamber via said second vacuum lock; substrates introducedvia said second vacuum lock pass under said second sputtering means fora predetermined amount of time to metalize said substrates; andsubstrates metalized by said second sputtering means exit said chambervia said first vacuum lock.
 17. A method of metalizing substratescomprising: providing a supply of substrates; introducing substrates toa vacuum chamber through a first vacuum lock; introducing substrates tosaid vacuum chamber through a second vacuum lock; passing substratesintroduced to said vacuum chamber via said first vacuum lock under firstsputtering means for a predetermined amount of time to metalize saidsubstrates; passing substrates introduced to said vacuum chamber viasaid second vacuum lock under second sputtering means for apredetermined amount of time to metalize said substrates; removing saidsubstrates metalized by said first sputtering means via said secondvacuum chamber; and removing said substrates metalized by said secondsputtering means via said first vacuum chamber.
 18. A method accordingto claim 17, wherein said supply of substrates comprises at least firstand second substrates kept separate by said method.
 19. A methodaccording to claim 18, wherein all said first substrates are introducedto said vacuum chamber via said first vacuum lock.
 20. A methodaccording to claim 19, wherein all said second substrates are introducedto said vacuum chamber via said second vacuum lock.
 21. A methodaccording to claim 20, wherein said first substrates travel in a firstlinear direction through said chamber and said second substrates travelin a second linear direction through said chamber.
 22. A methodaccording to claim 21, further comprising the step of maintaining thesubstrates in position in said vacuum chamber through use of lockingmeans associated with a centering pin used to position said substratesduring movement of said substrates between said vacuum locks.